Filter apparatuses of the kind set forth in the opening part of this specification are known, for example, from DE 10 2005 055 555 or SE 464 062. Such a filter apparatus generally has a housing having an inlet and an outlet, and a filter element in the housing. In that case, the filter element is generally substantially cylindrical. In addition, such filter apparatuses of the general kind set forth above have a filter cleaning element which can be introduced into the cylindrical filter element along the central axis thereof. That axial introduction of the filter cleaning element causes an increase in a flow speed in a region of an inner surface of the filter element by virtue of a reduction in cross-section, whereby substances adhering in the filter element are flushed away. Cleaning of such a filter element is therefore generally effected without contact by an increase in flow speed. Therefore, such filter apparatuses are also referred to as Bernoulli filters.
Such filter apparatuses or Bernoulli filters are used in a large number of industrial applications, for example in the petrochemical or pharmaceutical industry, in the energy economy, and also on ships.
Although contact-less self-cleaning of such filter apparatuses of the general kind set forth above represents a major advantage in the use of such filters, the structural size of such filter apparatuses is a particular disadvantage. In particular, the structural size is dependent on the size of the volume flow of liquid to be filtered, so that the throughput of liquid to be filtered is limited by virtue of structural size restrictions. A further disadvantage lies in the manner of cleaning the filter apparatus. During cleaning by means of the introduction of the filter cleaning element, the filter apparatus has to be operated with an increased pump output.